Digital radiography (DR) is increasingly accepted as an alternative to either film-based or computed radiography (CR) imaging technologies that rely on photosensitive film layers or photostimulable storage phosphors to capture radiation exposure and thus to produce and store an image of a subject's internal physical features. With digital radiography, the radiation exposure energy captured on radiation-sensitive layers is converted, pixel by pixel, to electronic image data which is then stored in memory circuitry for subsequent read-out and display on suitable electronic image display devices. Among the driving forces in the success of digital radiography is the ability to rapidly visualize and communicate stored images via data networks to one or more remote locations for analysis and diagnosis by the radiologist, without the delay that results when film is developed and checked, then packaged and mailed or sent by courier to a remote location or when the film is input to a separate scanner apparatus to provide digitized image data.
Flat panel digital radiographic (DR) imaging systems enjoy a number of advantages over conventional film-based or earlier computed radiography (CR) systems. Among its salient advantages is the capability of the DR system to obtain radiographic image data without the need for an operator or technologist to move, handle, process, or scan any type of imaging medium following exposure. Data downloaded directly from the DR receiver panel is then quickly available for viewing and diagnosis on-site or at any appropriately networked viewer workstation. Among its other advantages are the capability to work with existing hardware components that generate x-ray radiation and its reduced dependence on operator performance.
Due to their size, weight and expense, earlier flat panel digital radiographic (DR) imaging detectors were permanently mounted in table and wall bucky structures specially designed to accommodate them. Continuing improvements allow more compact and portable DR imaging cassettes that can be used with imaging systems that were originally designed for use with film and CR cassettes. It is envisioned that reduced weight and size may allow conformance of the DR cassette form factor to the ISO-4090 35×43 cm standard cassette profile. This would allow the DR cassette to be fitted into existing table or wall x-ray units that also conform to this standard and promises to expand the usability of DR detection as a retrofit to existing film and CR cassettes equipped x-ray rooms, obviating the need to upgrade or modify existing x-ray table and wall equipment, as is done currently, thus offering beneficial cost advantages. As a result, retrofit DR detectors would be usable with systems that are now limited only for use with film and CR detectors. Further, as the DR cassette is reduced in size and weight and thus becomes more portable, there are more potential applications for its use, including use of the DR cassette as a tethered device, that is, connected to a receiving system with one or more cables for power and data transmission, or even as an un-tethered device, capable of wirelessly transmitting image data to a nearby imaging apparatus, eliminating the need for a cumbersome interconnecting cable or cables.
In addition to reduced size and weight, it would be highly desirable to provide a truly portable digital detector that is untethered for wireless communication and contains on-board battery power. With these additional advantages, the portable DR detector can be easily retrofitted into existing x-ray imaging systems. This would help to provide a detector that can be readily moved from one location to another as needed, without the cumbersome requirements and risks imposed by the need to connect power or data cables.
While full portability of the DR cassette with wireless communication is a desirable goal, however, practical hurdles remain. Image capture components that sense received radiation and convert the sensed signal to digital data can be miniaturized and packaged within the DR cassette itself. However, it remains a challenge to compactly package the additional support circuitry that is needed in order to provide battery power for successive image captures and the circuitry that is needed for providing wireless communication with a remote system. Moreover, this full portability and untethered operation may not be necessary for all imaging systems; there can be systems for which tethered operation is fully acceptable.
Thus, it can be appreciated that there would be advantages to a DR cassette that can be used in either fully portable, untethered mode or with a tethered host and power supply connection.